The invention generally relates to valve devices for connecting two conduits in a unit for conducting a product.
The invention also relates to a unit for conducting a product in which at least two conduits are connected to one another via a valve device.
The invention furthermore relates to a method for operating such a unit.
Such a valve device is used in a unit, for example a food processing unit, a pharmaceuticals processing unit or a gene engineering unit, for connecting two conduits to each other in order to reliably separate the processes running in both of the conduits from each other, or else to transfer the process running in the one conduit into the other conduit.
In a food processing unit, a food product, for example milk or a milk product, can flow, for example, in one conduit and a cleaning medium can flow in the other conduit, the cleaning medium being used to clean the other conduit. In the latter case, it is particularly important for the two shut-off members to reliably separate the opposing media flowing in the two conduits from each other because, for example, mixing of the food product flowing in the one conduit with the cleaning medium flowing in the other conduit would spoil the food product.
The leakage space between the two shut-off members serves to make a leakage of one or both shut-off members apparent by the leakage space being monitored with regard to a leakage of medium from one of the two conduits into the leakage space, for example by means of a sensor or simply by visual checking.
The valve device known from DE 42 43 111 A1 is an aseptic double seat valve which ensures that the requirements of reliably separating different processes in the two conduits from each other are met and also satisfies aseptic conditions. Nevertheless, said known valve device has the following disadvantages.
A first disadvantage arises during the cleaning of one of the two shut-off members. For example, when the second shut-off member is cleaned, it is opened such that cleaning medium supplied through the second conduit cleans the second shut-off member and the leakage space. However, it is then not possible, at least under the strict regulations of the Process Milk Ordinance (PMO) standard to allow a product to flow in the first conduit while the second shut-off member is being cleaned. This is because the abovementioned PMO standard requires the presence of a steam barrier between the cleaning process and the product process, at least if the latter is an aseptic product process, said steam barrier additionally separating the product process from the cleaning process. Under these strict regulations, it is therefore compulsory to interrupt the product process in the other conduit for the duration of the cleaning process. This leads to the disadvantage of reduced productivity and economic efficiency of the unit.
A further disadvantage of the known valve device is that an existing unit for conducting a product and having the known valve device can be expanded only with limited functionality. This is explained below with reference to FIGS. 1a) to d).
FIG. 1a) shows a prior art unit for conducting a product 100′, which unit is installed, for example, in a food processing factory.
In its starting state as per FIG. 1a), the unit for conducting a product 100′ has, for example, a single sterilizer 102′a, an aseptic buffer tank 104′a and a filling group 106′a with two filling stations F11 and F12. A conduit 108′a leads away from the buffer tank 104′a and is connected to a conduit 110′a, which, in turn, is connected to the sterilizer 102′a, and to a conduit 112′a which leads to the filling group 106′a. At a first junction point 114′a, the conduit 108′a is connected to the conduit 112′a via a known valve device, as described above, and, at a junction point 116′a, the conduit 108′a is likewise connected to the conduit 110′a via a known valve device as described above.
The filling group 106′a is designed, for example, for filling a product into containers made of multi-layered material. The functionality of the unit 100′ as per FIG. 1a) consists in the sterilizer 102′a transferring a product via the conduits 110′a, 108′a and 112′a to the filling group 106′a, it being possible for the product to be temporarily stored in the buffer tank 104′a depending on the balance between supply and demand at the filling group 106′a. The known valve devices located at the junctions 114′a, 116′a are appropriately switched for this purpose.
FIG. 1b) now shows the unit 100′ as per FIG. 1a) in an expansion stage which would be required, for example, because of increased capacity of the factory in which the unit 100′ is being operated.
In said expansion stage, the unit 100′ additionally has a second filling group 106′b with which, for example, containers having different volumes than in the filling group 106′a can be filled. In order to increase the buffer capacity, a second buffer tank 104′b has been installed, but the latter is connected via the junction 114′b only to the filling group 106′b, but not to the filling group 106′a. Therefore, the filling group 106′a cannot be supplied with product from the buffer tank 104′b, and the filling group 106′b cannot be supplied with product from the buffer tank 104′a. 
FIG. 1c) shows a second expansion of the unit 100′ which has become necessary, for example, because the buffer capacity has additionally had to be increased by a third buffer tank 104′c, and, in addition, it has furthermore become necessary to install a second sterilizer 102′b in the factory in which the unit 100′ is being operated in order to be able to increase the sterilizing capacity of the unit 100′ and/or to be able to use a different type of sterilization. Furthermore, the unit 100′ has been expanded by a third filling group 106′c with which, for example, plastic bottles can be filled.
As emerges from FIG. 1c), the buffer tank 104′a continues to be connected only to the filling group 106′a, the buffer tank 104′b only to the filling group 106′b, and the newly added buffer tank 104′c only to the filling group 106′c, and, in addition, the newly added sterilizer 102′b is connected only to the buffer tank 104′c. As emerges from FIG. 1c), supplying of the product via the sterilizer 102′b into the buffer tank 104′a and from there into the filling group 106′b, for example, is not possible, nor are other combinations. The functionality of the unit 100′ is therefore increased only to a limited extent by the expansion. Connections are provided only at the junction points shown.
FIG. 1d) finally shows a third expansion of the unit 100′ by a fourth buffer tank 104d in order to further increase the buffer capacity of the unit 100′.
In contrast to FIG. 1c), a valve matrix 120′ comprising conventional valve devices was additionally installed here between the buffer tanks 104′a to 104′d and the filling groups 106′a-c such that product can be supplied from each buffer tank 104′a to 104′d into each filling group 106′a to 106′c. 
However, said valve matrix 120′ does not solve the problem of the two sterilizers 102′a and 102′b continuing to be connected only to certain of the buffer tanks 104′a to 104′d, as a result of which the full functionality of the unit 100′ continues not to be achieved yet. The productivity of the unit 100′ therefore continues to be subject to restrictions because it is not possible, for example, to fill the buffer tanks 104′a and 104′b via the sterilizer 102′b. 
On account of the abovementioned disadvantages, there continues to be a demand for a valve device which, firstly, makes it possible to reliably separate processes in the two conduits, which it connects, without, when there is a cleaning process on one side of the valve device, a product process on the other side of the valve device having to be interrupted, and, in particular if an existing unit for conducting a product is expanded, the valve device also permits the greatest possible functionality of the expanded unit without the use of an additional valve matrix.